Photoinitiated tissue filler

ABSTRACT

Visible light-activated polymer cosmetic filler preparations useful in a variety of applications are provided. In some embodiments, the photo-activated polymer composition comprises a conventional polymeric material, such as HA, together with a modified, cross-linkable polymer, such as PEG or PEODA, to permit the formation of crosslinks within the polymer matrix in situ on exposure to a visible light source, such as an IPL device. The preparations provide for a more stabilized composition that is contourable during gelation.

This application claims the benefit of U.S. provisional application No.60/953,375 filed Aug. 1, 2007, which is incorporated herein by referencein its entirety.

BACKGROUND OF INVENTION

Hyaluronic acid (HA), which can be crosslinked, and collagens arebiomaterials used in the fields of surgery and dermatology as fillers torecontour/reconstruct tissues. The market of cosmetic fillers for softtissue augmentation has increased in recent years and there is a need tocreate longer lasting materials that are retained at the site ofapplication. Physicians also would like to improve control over thefinal result and allow for subsequent correction to optimize patientsatisfaction.

Hydrogels hold the promise of creating dermal fillers that maintainaesthetic corrections longer than currently available fillers. The term,“hydrogel,” refers to a broad class of polymeric materials that containwater but do not dissolve in water. Generally hydrogels are cross-linkedand networked polymer chains. If there are two or more crosslinks perpolymer chain, a network is formed that is able to absorb large amountsof solvent. Hydrogels are of particular interest in the field of tissueengineering because of their tissue-like water content, which allowsnutrient and waste transport.

There are a number of methods to form polymers and to crosslinkpolymers. One such method involves light-reactive reagents andlight-induced reactions which create reactive species in a monomersolution, wherein the monomers are polymerized to form chains, monomers,polymers and chains, which in turn can form networks.

Currently used cosmetic fillers are generally derived from biologicalpolymers, such as collagen or hyaluronic acid. Since these compounds arebiological in nature, they tend to be sensitive to degradation even ifcrosslinked. Hence, the esthetic duration of an enhancement/correctionachieved with such materials is limited in time, and frequently requiresthe recipient to undergo additional and expensive repeatinjections/treatments to maintain a desired effect. Another drawback ofconventional cosmetic fillers is the lack of malleability andcontourability to maintain a desired and/or corrective formation afterinjection, such as, for example, in human cheek bone or chinmanipulations. Thus, for these types of and other similar procedures, amore invasive approach is used wherein plastic implants are insertedwhile a patient is under general anesthesia. Hence, a need continues toexist in the cosmetic reconstructive arts for improved polymeric fillersthat are contourable and longer lasting.

Synthetic polymers have highly controllable physical and degradationproperties, making them suitable for creating an implant with specificproperties. Poly(ethylene glycol), PEG, is an example of a frequentlyused biocompatible synthetic polymer. PEG, and other synthetic polymers,can be modified to react with functional groups to allow crosslinkingand to form hydrogels.

A PEG derivative, poly(ethylene oxide) diacrylate (PEODA), can beinjected into the body as a solution and can be polymerized to form acrosslinked, insoluble gel [1-5]. To induce photopolymerization by freeradical formation, various photoinitiators have been used. Inparticular, Hubbell and his colleagues previously created PEODAhydrogels using Eosin Y/triethylamine via argon ion laser (514 nm, 70mW/cm², 2 s exposure; American Laser, Salt Lake City) [6]. Eosin Y is agood candidate as a transdermal photoinitiator because of its adsorptionrange in visible blue light [7,8]. The advantage of visible light, ascompared to UV, is that the longer visible wavelength can penetratedeeper into the skin. Moreover, high doses of UV light have beenimplicated as a cause for erythema and different types of skin cancers[9]. Therefore, photopolymerization using a visible light source wouldbe suitable for the proposed cosmetic applications. Feasibility of PEODAphotopolymerization with visible light using Eosin Y as the initiatorunder human skin, however, is yet to have been established.

Intense pulsed light (IPL) devices are a common visible light source ina dermatology office for photorejuvenation and photoepilation procedures[10-13]. The compatibility of Eosin Y photoinitiation with an IPLdevice, however, has not been established.

These and other deficiencies in the art of cosmetically usefulpreparations are satisfied with the present invention.

SUMMARY OF THE INVENTION

In part, the present disclosure provides novel cosmetic fillersactivated by visible light that comprise a crosslinkable polymericmaterial or functional derivatives thereof. The polymers and derivatizedpolymeric materials may be further described as containing modifiedreactive groups that facilitate polymerization, attachment andcrosslinking of the polymeric material on exposure to light. By exposureto visible light, the liquid form of the synthetic polymer filler in thecosmetic preparation takes on a semisolid or gel form, and is amenableto desired contouring and manipulation to result in a desired, solidand/or semisolid polymerized form in situ. Moreover, the use ofderivatized monomers and polymers provides for more stable polymers andnetworks that are more resistant to biodegradation.

Virtually any polymeric material that may be modified to include alight-activated derivatized reactive group may be used in thepreparation of the present cosmetic fillers. By way of example, and notlimitation, and in particular embodiments, the polymer can comprisesynthetic reactants and comprises poly(ethylene glycol) (PEG) or aderivative thereof. In some embodiments, the polymer derivativecomprises poly(ethylene oxide) diacrylate (PEODA) or poly(ethyleneglycol) diacrylate (PEGDA).

In another aspect, the invention provides for a method for forming animplant in vivo. In particular embodiments, the method comprisesadministering a liquid derivatized monomeric material into a desiredsite in a host, inducing gelation to form a polymeric material byexposing said liquid derivatized monomeric material to light, andcontouring said gelling and gelled polymeric material into a desiredconformation to provide an implant.

In particular applications, the liquid derivatized polymeric materialcomprises a combination of a PEODA/Restylene® (a commercially availablefiller, U.S. Pat. No. 5,827,937) solution. In some embodiments, thePEODA/Restylene® solution comprises 10% PEODA, 15% PEODA, 20% PEODA, 25%PEODA, 30% PEODA, 35% PEODA, 40% PEODA, 45% PEODA, 50% PEODA, 60% PEODA,70% PEODA or even up to 80% PEODA.

In some embodiments, a photoinitiator is included in the method or in areagent of the method. In some embodiments, the photoinitiator will beone responsive to visible light, such as one with an absorption maximumin the visible blue light range. An example of such a photoinitiatorhaving an absorption maximum in the visible blue light range is Eosin Y.

In specific applications of the method, a 10% PEODA or a 20% PEODAsolution will be used in combination with 200 mM triethylamine and 50uL/ml Eosin Y initiator.

In some embodiments of the method, the illumination means used is anintense pulsed light (IPL) source. In some embodiments of the method, acombination of Eosin Y/triethylamine and an IPL light source is used toprovide a tissue filler or implant. In some embodiments, theillumination means is one wherein the light penetrates the skin, thatis, the illumination means is placed above or on the skin, and thevisible light is applied to the skin surface.

Compositions of the present disclosure may further comprise a cell, orencapsulated cells, tissues and/or engineered cells and tissues.

The present invention is envisioned to embrace any number of differentcombinations and concentrations/amounts of synthetic polymers,biodegradable polymers, photoinitiators, proton acceptors, visible lightsources and pulse intensity and schedule regimens, and is expected tovary depending on the particular subject being treated, the particulartype and location of cosmetic implant/cosmetic filler sought to beachieved, the viscosity and specific physical properties of the cosmeticfiller suitable for the specific application being made, as well asother variables associated with clinical procedures of this type knownto those of ordinary skill in the cosmetic and medical arts.

One advantage of the present materials/methods is an increasedresidence/lifetime of fillers and implants in vivo, Another advantage isan improved non-invasive method for providing an implant or filler thatmay be contoured to a particular subject and/or tissue site in situ. Yetanother advantage is the use of visible light which can be applied tothe skin surface.

In particular aspects, a composition suitable for tissue augmentation isprovided that comprises: (a) modified hyaluronic acid; (b) PEODA; and(c) accelerant of polymerization of the PEODA. Preferably, the PEODA hasa molecular weight (e.g. weight average molecular weight) in excess of2000, 2500, or 3000, with a molecular weight (e.g. weight averagemolecular weight) of about 3400 being particularly preferred for manyapplications. Suitable accelerants may include e.g. N-vinylpyrrolidinone. A particularly preferred modified hyaluronic acid isRestylane™. Such preferred compositions also may suitably comprise aninitiator e.g. Eosin Y as well as co-initiator (i.e. a composition thathas at least two distinct initiators) such as an amine e.g. a tertiaryamine. A trialkyl amine such as triethyl amine or othertri(C₁-C₁₆alkyl)amine can be a preferred co-initiator. In suchcompositions the weight ratios of PEODA to modified hyaluronic acid cansuitably vary rather widely, preferably with PEODA being present in aweight excess relative to the modified hyaluronic acid component, e.g.where the w/w ratio of PEODA:modified hyaluronic acid is from about 2:1to 10:1. Particularly suitable w/w ratios of PEODA:modified hyaluronicacid include 10:1, 5:1 and 2:1.

In a further particularly preferred aspect, methods are provided foraugmenting a soft tissue site comprising: (a) administering to the softtissue site a composition comprising: PEODA monomers, modifiedhyaluronic acid, and an accelerant; and (b) applying light to the tissuesite to induce polymerization of the PEODA monomers. The soft tissuesite is suitably that of a mammal, particularly a primate such as ahuman, e.g. the neck, orbital groove, breast, cheek and/or nose of sucha subject. Suitably the light may be applied externally to the subject.Preferably, such methods also may comprise shaping the soft tissue siteby external manipulation. The composition may be administered to thesoft tissue site by any of a number of suitable means, such as byinjection under the skin. Preferably, the PEODA has a molecular weight(e.g. weight average molecular weight) in excess of 2000, 2500, or 3000,with a molecular weight (e.g. weight average molecular weight) of about3400 being particularly preferred for many applications. Suitableaccelerants may include e.g. N-vinyl pyrrolidinone. A particularlypreferred modified hyaluronic acid is Restylane™.

Other aspects of the invention are disclosed infra.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B—HA-based filler with PEG crosslinked using light in asubcutaneous space of a mouse retained more volume over the 140 daysstudied (FIG. 1A). Specific comparison after 28 days (FIG. 1B) definesmore clearly the differences between the two groups.

DETAILED DESCRIPTION

The instant invention relates, in part, to cosmetic and medicalpolymer-based fillers that form a moldable gel or gel-like compositionon photoactivation with a visible light source. The polymer may benaturally occurring or synthetic.

Significant to a product of interest is the advantage of permitting insitu formation of a custom, contoured filler or implant without invasivesurgical intervention or general anesthesia. Generally, the product ofinterest is introduced under the skin (that is, under the epidermis) andpolymerization is induced by exposure to visible light applied to theskin surface, that is, from outside of the body or outside of the skin,or to the epidermis.

The instant invention addresses the problem of limited lifetime ofcosmetic filler materials, particularly polymeric implantable materials.In some embodiments, the in vivo lifetime of implants and/or otherformations made with the present polymer-based preparations, such asPEODA, is increased by 50% or more, such as by 60%, by 70%, by 75%, by80%, by 85%, by 90% or even up to 100%, compared to conventional implantmaterials.

The instant invention provides for in situ polymerization techniques toprovide cosmetic and medical corrective and/or enhancement proceduresusing conventional polymeric materials that include a polymer componentcapable of forming an insoluble crosslinked and crosslinking network onactivation with a visible light source.

For example, the instant disclosure provides a cosmetic filler thatcomprises PEG, or a derivative thereof, such as PEODA, either alone ortogether with another polymer, such as HA, which may be crosslinked, toprovide a cosmetic filler that forms a water insoluble, crosslinkedpolymer preparation in situ on visible light activation in the presenceof a photoinitiator, such as Eosin Y, optionally, in the presence of aproton acceptor, such as, triethylamine.

A biological surface refers to an external (relative to a tissue ororgan, for example), exposed portion of a biological material or entity,such as a skin surface, cell, tissue, organ and the like, to which apreparation comprising the light-activated crosslinkable monomerpreparation of interest can be exposed or is applied and then saidpreparation is induced to form a gel in situ on said surface forcosmetic and/or corrective use.

A biologically compatible polymer refers to a polymer which isfunctionalized to serve as a composition for applying to a biologicalsurface. The polymer is one that is a naturally occurring polymer or onethat is not toxic to the host, The polymer may be a homopolymer whereall monomers are the same or a heteropolymer containing two or morekinds of monomers. The terms, “biocompatible polymer,” “biocompatiblecross-linked polymer matrix” and “biocompatibility,” when used inrelation to the instant polymers are art-recognized and are consideredequivalent to one another, including, “biologically compatible polymer.”For example, biocompatible polymers include polymers that are naturallyoccurring, or are polymers that can be synthetic, and which are neithertoxic to the host (e.g., an animal or human) nor degrade (if the polymerdegrades) at a rate or that produces monomeric or oligomeric subunits orother byproducts at toxic concentrations or which are toxic in the host.

In certain embodiments of the present invention, biodegradationgenerally involves degradation of the polymer in an organism, e.g., intoits monomeric subunits, which may be known to be effectively non-toxic.Intermediate oligomeric products resulting from such degradation mayhave different toxicological properties, however, or biodegradation mayinvolve oxidation or other biochemical reactions that generate moleculesother than monomeric subunits of the polymer. Consequently, in certainembodiments, toxicology of a biodegradable polymer intended for in vivouse, such as implantation or injection into a patient, may be determinedafter one or more toxicity analyses. It is not necessary that anysubject composition have a purity of 100% to be deemed biocompatible;indeed, it is only necessary that the subject compositions bebiocompatible as set forth above, Hence, a subject composition maycomprise polymers comprising 99%, 98%, 97%, 96%, 95%, 90%, 85%, 80%, 75%or even less of biocompatible polymers, e.g., including polymers andother materials and excipients described herein, and overall still bebiocompatible and minimally or not toxic.

To determine whether a polymer or other material is biocompatible, itmay be necessary to conduct a toxicity analysis. Such assays are wellknown in the art. One example of such an assay may be performed withlive cells, such as HeLa, 293, CHO and the like. The polymer sample ispartially or completely degraded as known in the art, using for example,chemical means or enzymatic means. An aliquot of the treated sampleproducts is placed in culture plates previously seeded with the cells.The sample products are incubated with the cells. The results of theassay may be plotted as % relative growth vs. concentration of degradedsample. Non-degraded polymer, monomers, networks and the like can betested as well.

In addition, monomers, polymers, polymer matrices, and formulations ofthe present invention may also be evaluated by well-known in vivo tests,such as subcutaneous implantation in rats to confirm that the materialsof interest do not cause significant levels of, for example, irritationor inflammation at the subcutaneous implantation sites,

An “active agent” and a “biologically active agent” are phrases usedinterchangeably herein to refer a chemical or biological compound thatinduces a desired pharmacological or physiological effect, wherein theeffect may be prophylactic or therapeutic. The terms also encompasspharmaceutically acceptable, pharmacologically active derivatives ofthose active agents specifically mentioned herein, including, but notlimited to, salts, esters, amides, prodrugs, active metabolites, analogsand the like. When the terms “active agent,” “pharmacologically activeagent” and “drug” are used, it is to be understood that the inventionincludes the active agent per se, as well as pharmaceuticallyacceptable, pharmacologically active salts, esters, amides, prodrugs,metabolites, analogs etc. The active agent can be a biological entity,such as a virus or cell, whether naturally occurring or manipulated,such as transformed.

Crosslinked herein refers to a composition containing intermolecularlinks and, optionally, intramolecular links, arising from the formationof covalent bonds. Covalent bonding between two crosslinkable componentsmay be direct, in which case, an atom in one component is directly boundto an atom in the other component, or it may be indirect, that is, forexample, through a linking group. A crosslinked gel or polymer matrixmay, in addition to covalent bonds, also include intermolecular and/orintramolecular noncovalent bonds such as hydrogen bonds andelectrostatic (ionic) bonds.

Functionalized refers to a modification of an existing molecular segmentto generate or introduce a new reactive or more reactive group (e.g., anamine, ester or imide group) that is capable of undergoing reaction withanother molecule, polymer or functional group (e.g., an amine, an esteror a carboxyl group) to form a covalent bond. For example, carboxylicacid groups can be functionalized by reaction with a carbodiimide and animide reagent using known procedures to provide a new reactivefunctional group in the form of an imide group substituting for thehydrogen in the hydroxyl group of the carboxyl function.

Gel refers to a state of matter between liquid and solid, and isgenerally defined as a polymer network swollen in a liquid medium.Typically, a gel is a two-phase colloidal dispersion containing bothsolid and liquid, wherein the amount of solid is greater than that inthe two-phase colloidal dispersion referred to as a “sol.” As such, a“gel” has some of the properties of a liquid (i.e., the shape isresilient and deformable) and some of the properties of a solid (i.e.,the shape is discrete enough to maintain three dimensions on atwo-dimensional surface). “Gelation time,” also referred to herein as“gel time,” refers to the time it takes for a composition to becomenon-flowable under modest stress. This is generally exhibited asreaching a physical state in which the elastic modulus, G′, equals orexceeds the viscous modulus, G″, i.e., when tan(A) becomes 1 (as may bedetermined using conventional rheological techniques).

A gel that is “moldable” is one that is conformable to a shape before orduring exposure to the light, and which can be contoured or shaped toassume and to retain a particular shape. Thus, following instillation oradministration in a space and illumination to catalyze gelation, acomposition of interest can be shaped by external manipulation, using,for example, a shaping means, such as, a surgical depressor or othertool or instrument with a flat or curved surface, fingers, the palm, aknuckle and so on.

A hydrogel is a water-swellable polymeric matrix that can absorb waterto form elastic gels. Hydrogels consist of hydrophilic polymerscrosslinked to from a water-swollen, insoluble polymer network.Crosslinking can be initiated by many physical or chemical mechanisms,for example, such as, a light-induced reaction.

A “matrix” is a three-dimensional network of macromolecules heldtogether by covalent or noncovalent crosslinks. On placement in anaqueous environment, dry hydrogels swell to the extent allowed by theviscosity, the gel state and/or degree of crosslinking in the polymer ornetwork. A matrix can be a network.

Photopolymerization is a method to covalently crosslink polymer chains,whereby a photoinitiator and polymer solution (termed “pre-gel” ormonomer solution) are exposed to a light source specific to thephotoinitiator. On activation, the photoinitiator reacts with specificfunctional groups in the polymer chains, linking the functional groupsto form the hydrogel. The reaction generally is rapid (3-5 minutes) andcan proceed at room or body temperature. Photoinduced gelation enablesspatial and temporal control of scaffold formation, permitting shapemanipulation after injection and during gelation in vivo. Cells andbioactive factors can be incorporated into the hydrogel scaffold bysimply mixing same in and with the polymer solution prior to gelation.

Hydrogels of interest can be semi-interpenetrating networks that promotecell, tissue and organ repair while discouraging scar formation. Thehydrogels of interest are derivatized to contain a reactive group tofacilitate polymerization and linking. The hydrogels of interest alsocan carry a reactive group or a functional group reactive with abiological surface, an artificial surface and/or a second polymer ornetwork. The latter form of reactivity also can anchor a gel of interestat and to a site of interest, Hydrogels of interest also are configuredto have a viscosity that will enable the gelled hydrogel to remain orreside in place for longer periods of time. Viscosity can be controlledby the monomers and polymers used, the degree of crosslinking, by thelevel of water trapped in the hydrogel and by incorporated thickeners,such as biopolymers, such as proteins, lipids, saccharides and the like.An example of such a thickener is HA, whether crosslinked or not.

Polymer is used to refer to molecules composed of repeating monomerunits, including homopolymers, block copolymers, heteropolymers, randomcopolymers, graft copolymers and so on. “Polymers” also include linearpolymers as well as branched polymers, with branched polymers includinghighly branched, dendritic, comb-burst and starburst polymers.

A monomer is the basic repeating unit in a polymer. A monomer may itselfbe a monomer or may be dimer or oligomer of at least two same ordifferent monomers, and each dimer or oligomer is repeated in a polymer.A macromer, a macromolecular weight monomer, is generally a polymer oroligomer with a reactive group, often at a terminus, which enables themolecule to act as a monomer.

A polymerizing initiator refers to any substance that can initiatepolymerization of monomers or macromers by, for example, free radicalgeneration. The polymerizing initiator often is an oxidizing agent.Exemplary polymerizing initiators include those which are activated byexposure to, for example, electromagnetic radiation, such as visiblelight.

Certain monomeric subunits of the present invention may exist inparticular geometric or stereoisomeric forms. In addition, polymers andother compositions of the present invention may also be opticallyactive. The present invention contemplates all such compounds, includingcis-isomers and trans-isomers, R-enantiomers and S-enantiomers,diastereomers, (d)-isomers, (1)-isomers, the racemic mixtures thereof,and other mixtures thereof, as falling within the scope of theinvention. Additional asymmetric carbon atoms may be present in asubstituent, such as an alkyl group. All such isomers, as well asmixtures thereof, are intended to be included in the invention.

The terms “substituted,” “functional group” and “reactive group” arecontemplated to include all permissible substituents of organiccompounds on the monomers, polymers and networks of interest. In a broadaspect, the permissible substituents include acyclic and cyclic,branched and unbranched, carbocyclic and heterocyclic, aromatic andnonaromatic substituents of organic compounds. Illustrative substituentsinclude, for example, carboxy groups, amine groups, amide groups,hydroxyl groups and so on, as known in the art. The permissiblesubstituents may be one or more and the same or different forappropriate organic compounds. For purposes of this invention, theheteroatoms such as nitrogen may have hydrogen substituents and/or anypermissible substituents of organic compounds described herein whichsatisfy the valences of the heteroatoms. This invention is not intendedto be limited in any manner by the permissible substituents of organiccompounds.

A functional group or a moiety capable of mediating formation of apolymer or network can be added to a naturally occurring molecule or asynthetic molecule practicing methods known in the art. Functionalgroups include the various radicals and chemical entities taught herein,and include alkenyl moieties such as acrylates, methacrylates,dimethacrylates, oligoacrylates, oligomethacrylates, ethacrylates,itaconates or acrylamides. Further functional groups include aldehydes.Other functional groups may include ethylenically unsaturated monomersincluding, for example, alkyl esters of acrylic or methacrylic acid suchas methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylacrylate, butyl acrylate, hexyl acrylate, n-octyl acrylate, laurylmethacrylate, 2-ethylhexyl methacrylate, nonyl acrylate, benzylmethacrylate, the hydroxyalkyl esters of the same acids such as2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and2-hydroxypropyl methacrylate, the nitrite and amides of the same acidssuch as acrylonitrile, methacrylonitrile, and methacrylamide, vinylacetate, vinyl propionate, vinylidene chloride, vinyl chloride, andvinyl aromatic compounds such as styrene, t-butyl styrene and vinyltoluene, dialkyl maleates, dialkyl itaconates, dialkylmethylene-malonates, isoprene and butadiene. Suitable ethylenicallyunsaturated monomers containing carboxylic acid groups include acrylicmonomers such as acrylic acid, methacrylic acid, ethacrylic acid,itaconic acid, maleic acid, fumaric acid, monoalkyl itaconate includingmonomethyl itaconate, monoethyl itaconate, and monobutyl itaconate,monoalkyl maleate including monomethyl maleate, monoethyl maleate, andmonobutyl maleate, citraconic acid and styrene carboxylic acid. Suitablepolyethylenically unsaturated monomers include butadiene, isoprene,allylmethacrylate, diacrylates of alkyl dials such as butanedioldiacrylate and hexanediol diacrylate, divinyl benzene and the like.

It will be understood that substitution or substituted with includes theimplicit proviso that such substitution is in accordance with thepermitted valency of the substituted atom and the substituent, and thatthe substitution results in a stable compound, e.g., which does notspontaneously undergo transformation, such as by rearrangement,cyclization, elimination or other reaction.

For purposes of the invention, the chemical elements are identified inaccordance with the Periodic Table of the Elements, CAS version,Handbook of Chemistry and Physics, 67th Ed., 1986-87.

In some embodiments, the disclosure is directed to a compositioncomprising a cosmetic filler generally derived from biological polymerssuch as collagen or hyaluronic acid. In some embodiments, the polymersare generally linked to produce desired viscosity and physicalproperties. Those starting molecules are natural components ofextracellular matrices. Other suitable polymers include those which alsoare naturally occurring, such as a glycosaminoglycans,mucopolysaccharides, collagens or proteoglycan components, such ashyaluronic acid, heparin sulfate, glucosamines, dermatans, keratins,heparins, hyalurunan, aggrecan and the like. In general, anybiologically compatible polymer can be used as the polymer of interest.

Suitable hydrophilic polymers to serve as polymer of interest includesynthetic polymers such as poly(ethylene glycol), poly(ethylene oxide),partially or fully hydrolyzed poly(vinyl alcohol),poly(vinylpyrrolidone), poly(ethyloxazoline), polyethyleneoxide)-co-poly(propylene oxide) block copolymers (poloxamers andmeroxapols), poloxamines, carboxymethyl cellulose, and hydroxyalkylatedcelluloses such as hydroxyethyl cellulose and methylhydroxypropylcellulose, and natural polymers, such as, polysaccharides orcarbohydrates such as Ficoll™, polysucrose, dextran, heparan sulfate,chondroitin sulfate or alginate, and polypeptides or proteins such asgelatin, collagen, albumin or ovalbumin, or copolymers or blendsthereof. As used herein, “celluloses” includes cellulose and derivativesof the types described above; “dextran” includes dextran and similarderivatives thereof.

In some embodiments, a monomeric unit of a biologically compatiblepolymer may be functionalized through one or more thio, carboxylic acidor alcohol moieties located on a monomer of the biopolymer. For example,in the case of chondroitin sulfate, a carbonyl group can be derivatizedwith a imide group using, for example, carbodiimide chemistry. Analcohol group can be derivatized using, for example, the Mitsunobureaction, Procter et al., Tetra. Lett. 47(29) 5151-5154, 2006.

Polysaccharides that are very viscous liquids or that are thixotropic,and form a gel over time by the slow evolution of structure, are alsouseful. For example, hyaluronic acid, which can form an injectable gelwith a consistency like a hair gel, may be utilized. Modified hyaluronicacid derivatives are particularly useful. As used herein, the term“modified hyaluronic acids” refers to chemically modified hyaluronicacids. Modified hyaluronic acids may be designed and synthesized withpreselected chemical modifications to adjust the rate and degree oflinking and biodegradation. For example, modified hyaluronic acids maybe designed and synthesized to be esterified with a relativelyhydrophobic group such as propionic acid or benzylic acid to render thepolymer more hydrophobic and gel-forming, or which are grafted withamines to promote electrostatic self-assembly. Modified hyaluronic acidsthus, may be synthesized which are injectable, to flow under stress, butmaintain a gel-like structure when not under stress. Hyaluronic acid andhyaluronic derivatives are available from Genzyme, Cambridge, Mass. andFidia, Italy.

Methods for the synthesis of the polymers described above are known tothose skilled in the art, see, for example Concise Encyclopedia ofPolymer Science and Polymeric Amines and Ammonium Salts, E. Goethals,ed. (Pergamen Press, Elmsford, N.Y. 1980). Many polymers, such aspoly(acrylic acid), are commercially available. Naturally occurringpolymers can be isolated from biological sources, as known in the art,or are commercially available. Naturally occurring and syntheticpolymers may be modified using chemical reactions available in the artand described, for example, in March, “Advanced Organic Chemistry,” 4thEdition, 1992, Wiley-Interscience Publication, New York.

Numerous chemical options are available for modifying polymers that maythen undergo a radical polymerization. For example, methacrylicanhydride, methacryloyl chloride and glycidyl methacrylate may be usedto add methacrylate groups to one or more monomers of a polymer chain.Glycidyl methacrylate may be used, for example, for efficiency ofreaction. Further, the modification reagents may be chosen to optimize alack of cytotoxic byproducts.

A variety of photolabile compounds are available, including, but notlimited to, disulfides, benzoins and benzyls for use as a photoinitiatorof interest. A non-limiting list of exemplary photoinitiators includesbenzophenone, trimethylbenzophenone, thioxanthone, 2-chlorothioxanthone,9,10-anthraquinone, bis-4,4-dimethylaminobenzophenone, benzoin ethers,benzilketals, α-dialkoxyacetophenones, α-hydroxyalkylphenones, α-aminoalkylphenones, acylphosphine oxides, benzophenones/amines,thioxanthones/amines, titanocenes, 2,2-dimethoxy acetophenone,1-hydroxycyclohexyl phenyl ketone,2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone,2-hydroxy-1-[4-(hydroxyethoxy)phenyl]-2-methyl-1-propanone,α-hydroxy-ketones and benzilidimethyl-ketals, e.g. Irgacure 651 and 184,and Darocur 1173, marketed by Ciba Chemicals, Rose Bengal,camphorquinone, erythrosine, and mixtures thereof, and so on.

The pregel, monomer solution can comprise a photoinitiator in an amountof, for example, 0.05 to about 1.5% by weight, 0.1 to 1.0% by weight or0.08 to 0.5% by weight, based on the entire polymerizable component tobe gelled, the degree of polymerization and/or networking desired, therate of polymerization and/or networking desired and so on, as a designchoice.

The monomer solution can contain the photoinitiator, the photoinitiatorcan be mixed with the monomer prior to use or applied separately.

Optionally, a proton acceptor is included. Suitable such protonacceptors are known in the art. An example of such a suitable protonacceptor is an amine, such as a tertiary amine, such as, triethylamine.

An illuminating means can be a light source suitable for activating thephotoinitiator used, and which can activate the photoinitiator fromoutside of the body. While thermal initiators can be used and thus, aninfrared source used, and ultraviolet-activated initiators can be used,and thus, a suitable ultraviolet source used, a preferred light sourceis a white light source. Thus, a suitable photoinitiator is used, suchas Eosin Y, so that the maximum absorption of the initiator and thelight source are tuned. As mentioned hereinabove, one such visible lightsource is an IPL device. A commonly used commercially available IPLcarries a xenon flash lamp. Other suitable light sources can be used solong as gelation occurs in the body, at the site, under the skin surfaceand so on, such as, by applying the electromagnetic radiation to thebody, to the site as needed, or from above the skin surface. Theelectromagnetic radiation is applied at an intensity, for a time and fora duration that enables gelation. The light source can be situated abovethe skin surface or directly on the skin surface.

The monomer solution of interest also can contain any of a variety ofother materials, such as, inert materials, such as, preservatives,fillers, excipients or diluents, pharmacologically active molecules oragents, such as a small molecule or a biological, cells and so on, asknown in the pharmaceutic arts. Thus, a suitable inert or biologicallyactive agent can be added to the monomer solution. In the case of thelatter, the active agent may exert a pharmacologic action locally at thesite or in the vicinity of the polymerized or networked structure ofinterest, or can be released from the formed scaffold, matrix or networkto move though the adjoining tissue spaces or may enter the circulatorysystem for a less local effect.

As discussed above, the functionalized monomer of interest also can beused in combination with other dermatology, orthopedic, cosmetic and soon fillers, patches and so on, such as those which are commerciallyavailable. Examples include Restylane^(4p), comprising a crosslinked HA,Juvederm (Allergan) comprising HA, Zyderm, comprising collagen,Radiesse™ comprising microspheres in a collagen and so on. Thus, themonomer solution of interest can be mixed with a known filler to providea composition which is moldable, contourable, has a long residence timeand so on.

By way of example, polymer matrix compositions of the invention can beused to block or fill various lumens and voids just below a skinsurface. Thus, the instant invention relates to a method of tissueaugmentation in a host, such as a human patient, wherein said monomersolution of interest is introduced at a site of interest using methodsknown in the art, such as injecting a monomer at or in a tissue site inneed of augmentation and once applied, exposing the body surface to avisible light to cause polymerization of the deposited monomer solution.A kit containing the injectable monomer, and a delivery means, such as asyringe, as well as an optional light source, a photoinitiator andproton acceptor, is also provided.

“Augmentation” means the repair, prevention or alleviation of defects,particularly defects due to loss or absence of tissue, by providing,augmenting, or replacing such tissue with a polymer or network orinterest. Augmentation is also meant to include supplementation of anatural structure or feature, that is, a building of adding to anexisting body part, for example, to increase the size thereof, such alips, nose, breast, ears, portions of the reproductive organs, eyebrows,chin, cheeks and so on. While the invention is designed primarily forsoft tissue augmentation, hard tissue augmentation is encompassed as theinjectable compositions of the invention can be applied to a hard tissueand can be used in combination with, for example, materials to promotemineralization or bone formation. Thus, tissue augmentation can includethe filling of lines, folds, wrinkles, minor facial depressions, cleftlips, superficial wrinkles and the like, such as, in the face and neck;the correction of minor deformities due to aging or disease, includingin the hands and feet, fingers and toes; the augmentation of the vocalcords or glottis to rehabilitate speech; the dermal filling of sleeplines and expression lines; the replacement of dermal and subcutaneoustissue lost due to aging; the augmentation of lips; the filling ofwrinkles and the orbital groove around the eye; the augmentation of thebreast; the augmentation of the chin; the augmentation of the cheekand/or nose; the filling of indentations in soft tissue, dermal orsubcutaneous, due to, e.g., overzealous liposuction or other trauma; thefilling of acne or traumatic scars and rhytids; the filling ofnasolabial lines, nasoglabellar lines and infraoral lines and so on.

The monomer solution of interest is one which has a viscosity suitablefor ready extrusion through a delivery means, such as a fine surgicalneedle (e.g., needles having a gauge of at least 22, at least 27 orfiner) at the temperature of use. Thus, a solution that is, “injectable”is one having a texture and viscosity which permits flow through asuitable delivery device, such as, a surgical needle, other surgicalinstrument, or other delivery means such as a equipment used inendoscopic or percutaneous dissectomy procedures, by employing typicalinjection pressures. The monomer solution of interest thus is injectablethrough a suitable applicator, such as a catheter, a cannula, a needle,a syringe, tubular apparatus and so on, as known in the art.

The viscosity of the monomer solution can be varied as a design choiceto suit the intended use. For example, for application to superficialsites or little tissue space volume, a less viscous monomer solution canbe used to ensure flowability of the solution. In other sites, such aslarger tissue spaces or deeper sites, a more viscous monomer solutioncan be used to facilitate retention of the monomer solution at the siteprior to and during exposure to the photoinitiator and light.

The instant invention also provides kits for enabling performing themethod of the invention. Such kits can be prepared from readilyavailable materials and reagents and can come in a variety ofembodiments as known in the pharmaceutic and medical arts. For example,such kits can comprise, in an amount sufficient for at least onetreatment, a photoactivatable monomer solution, optionally, sterilizedbuffers or water, other reagents necessary or helpful to perform themethod, and instructions. Instructions include a tangible expressiondescribing reagent concentration or at least one method parameter, suchas the amount of reagent to be used, stability conditions of thereagent(s) and the like, to allow the user to carry out the method ofthe instant invention. In one embodiment, a kit comprises a means fordelivery in which is placed a monomer of interest, which often ispre-sterilized. Such delivery means can include, by way of illustrationand not limitation, a small syringe (for example, 22 to 27 gauge), alarge syringe (for example, 13 to 19 gauge) or equipment used inendoscopic or percutaneous discectomy procedures, The delivery means canbe pre-sterilized and encased in a sterile containing means, such as aplastic wrapper. The reagents can be provided in solution, assuspensions, or as a substantially dry powder, e.g., in lyophilizedform, either independently or in a mixture of components to improve easeof use and stability. Where a degradable reagent is provided, conditionsare selected which maximize stability of the reagent(s), e.g., storageat lower temperature, addition of stabilizing agents (e.g., glycerol ora reducing agent) and so on, as known in the art. Unstable reagents canbe provided together with or separately from the more stable componentsof the kit. The reagents and instructions can be placed and carried in acontainer means for immobilizing the reagents therein thereby providingsupport and protection for the contents, providing stackability ofunits, providing insulation, providing a transporting form and so on.

The reagents are manufactured, kitted, stored and so on in a manneracceptable in the pharmaceutic arts, practicing methods and usingreagents that are suitable for in vivo use, as known in the art, see forexample, Remington: The Science and Practice of Pharmacy, latestedition.

The invention now being generally described, it will be more readilyunderstood by reference to the following examples which are includedmerely for purposes of illustration of certain aspects and embodimentsof the present invention, and are not intended to limit the invention.

Example 1 Dermal Filler Comprising PEG and HA

The present example demonstrates the utility of the present inventionfor providing a light-activated injectable cosmetic filler comprising amodified crosslinkable polymer together with HA.

A range of concentrations of PEG in HA filler (Restylane®) wereexamined. A blue dye was incorporated in the PEG to better visualize theimplant and the degradation thereof. Without PEG present, the HA quicklydissolved in the buffer solution. As more PEG was added to the filler,the shape (and incorporated dye) was maintained longer.

A suitable obtained concentration of PEG-HA was then translated to invivo studies, which demonstrated that incorporation of a crosslinkedpolymer with a commercially available dermal filler extended thelifetime of that filler. The data summarized and presented in FIG. 1demonstrated an enhanced retention of a dermal photofiller, thatincludes a combination of HA (Restylane) and PEG, by almost 100%,compared to HA (Restylane®) alone.

Example 2 Cosmetic Filler Comprising PEODA and HA

The present example demonstrates the utility of the present inventionfor providing a cosmetic filler composition that comprises HA and PEODA.

A number of polymer combinations were tested including varying polymerconcentrations and compositions. Those factors can play a role in themonomer properties, such as viscosity, crosslinking density andsubsequent swelling and mechanical properties of the hydrogel.

Macromer solutions: PEODA/HA (Restylene®) macromer solution was preparedby mixing 200 mM triethylamine (Sigma Aldrich),

50 pl/mL Eosin Y (Sigma Aldrich), N-vinylpyrrolidone (Sigma Aldrich),and PEODA (SunBio, Seoul, South Korea, molecular weight: 3400 g/mol) inRestylene®. Three different concentrations of PEODA were used: 4 and 10%PEODA and 20% 4-arm PEODA.

Then, the macromer solution was injected under the skin of a 78 year-oldfemale cadaver and was photopolymerized by IPL exposure (intensity perpulse, −5 J/cm²) under three different conditions.

Subcutaneous mold: Macromer solution of approximately 100 pL was put ina mold and placed under the skin. IPL light was shone, and the number ofIPL pulses required for polymerization of macromer solution was countedand recorded (Table 1).

Dermal pocket: Under the skin, a constrained space with a smooth surfacewas created, and macromer solution of approximately 500 pL was placed inthe pocket without a mold. IPL light was shone, and the number of IPLpulses required for polymerization of macromer solution was counted andrecorded (Table 1).

Intradermal injection: Macromer solution was injected under the skin.

Solidification of the macromer solutions was observed after differentIPL pulses were applied. Polymerization was confirmed following excisionof the site.

The distance from which the IPL light source was held from the skin hadan effect on polymerization, and macromer solutions were not polymerizedif the IPL source was held further than approximately 3 cm from thecadaver skin surface. Therefore, the IPL light source was kept about 1cm from the skin, and the amount of energy required forphotopolymerization of macromer solutions was determined (Table 1). Theresults indicated that the PEODA/Restylene® macromer solution indeed canbe polymerized in dermal and intradermal spaces using Eosin Y initiatorand IPL light source.

TABLE 1 Pulses Total Group Procedure (5 J/cm² per (J/cm²) PolymerizationRestylene ® + Subcutaneous 12 60 + 10% PEODA Mold Dermal 10 50 + PocketIntradermal 18 90 + Injection Restylene ® + Subcutaneous 12 60 + 4%PEODA Mold Dermal 14 70 − Pocket 18 90 + Intradermal 30 150 + InjectionRestylene ® + Subcutaneous 8 40 + 20% 4 arm Mold PEODA Dermal 6 30 +Pocket Intradermal 10 50 + Injection

All publications and patents mentioned herein are hereby incorporated byreference in their entirety as if each individual publication or patentwas specifically and individually indicated to be incorporated byreference.

BIBLIOGRAPHY

The following references are specifically incorporated herein in theirentirety by reference.

-   1. Elisseeff J, Anseth K, Sims D, McIntosh W, Randolph M, Langer R:    Transdermal photo polymerization for minimally invasive    implantation. Proc Natl Acad Sci USA 1999; 96:3104-3107.-   2. Williams C G, Kim T K, Taboas A, Malik A, Manson P, Elisseeff J:    In vitro chondrogenesis of bone marrow-derived mesenchymal stem    cells in a photopolymerizing hydrogel. Tissue Eng 2003; 9:679-688.-   3. Elisseeff J: Injectable cartilage tissue engineering. Expert Opin    Biol Ther 2004; 4:1849-1859.-   4. Elisseeff J, Anseth K, Sims D, McIntosh W, Randolph M, Yaremchuk    M, Langer R: Transdermal photo polymerization of poly(ethylene    oxide)-based injectable hydrogels for tissue-engineered cartilage.    Plast Reconstr Surg 1999; 104:1014-1022.-   5. Nguyen K T, West J L: Photopolymerizable hydrogels for tissue    engineering applications. Biomaterials. 2002; 23:4307-4314.-   6. Hill-West J L, Chowdhury S M, Slepian M J, Hubbell J A:    Inhibition of thrombosis and intimal thickening by in situ    photopolymerization of thin hydrogel barriers. Proc Natl Acad Sci    USA 1994; 91:5967-5971.-   7. Nakayama Y, Matsuda T: Photocurable surgical tissue adhesive    glues composed of photo reactive gelatin and poly(ethylene glycol)    diacrylate. Blamed Mater Res 1999; 48:511-521.-   8. Valdesaguilera O, Pathak C, Shi J, Watson D, Neckers D:    Photopolymerization studies using visible light photoinitiators.    Macro 1992; 25:541-547.-   9. Levine J A, Sorace M, Spencer J, Siegel D M: The indoor UV    tanning industry: a review of skin cancer risk, health benefit    claims, and regulation. J Am Acad Dermatol 2005; 53:1038-1044.-   10. Marayiannis K B, Vlachos S P, Savva M P, Kontoes P P: Efficacy    of long- and short pulse alexandrite lasers compared with an intense    pulsed light source for epilation: a study on 532 sites in 389    patients. J Cosmet Laser Ther 2003; 5:140-145.-   11. Negishi K, Kushikata N, Takeuchi K, Tezuka Y, Wakamatsu S:    Photorejuvenation by intense pulsed light with objective measurement    of skin color in Japanese patients. Dermatol Surg 2006;    32:1380-1387.-   12. Goldman M P, Weiss R A, Weiss M A: Intense pulsed light as a    nonablative approach to photoaging. Dermatol Surg 2005;    31:1179-1187; discussion 1187.-   13. Sadick N S, Weiss R, Kilmer S, Bitter P: Photorejuvenation with    intense pulsed light: results of a multi-center study. J Drugs    Dermatol 2004; 3:41-49.

1-36. (canceled)
 37. A method of repairing or augmenting soft tissue ina subject, the method comprising a. injecting into a subject in needthereof a composition comprising a biodegradable, polymerizablemacromer, the macromer comprising a water soluble polymer modified withone or more biodegradable moieties; and b. polymerizing the macromer toprovide a hydrogel wherein the hydrogel to soft tissue have a normalizedcompliance ratio of from about 0.05 to about 3, thus repairing oraugmenting the soft tissue.
 38. The method of claim 37, wherein thecompliance ratio is from about 0.1 to about 2.0 relative to the softtissue.
 39. The method of claim 38, wherein the compliance ratio is fromabout 0.1 to about 1.0 relative to the soft tissue.
 40. The method ofclaim 37, wherein the macromer is polymerized by irradiating through theskin of the subject with visible light.
 41. The method of claim 37,wherein the subject is irradiated with visible light for from about 10seconds to about 120 seconds.
 42. The method of claim 41, wherein thesubject is irradiated with visible light for at least about 30 seconds.43. The method of claim 42, wherein the subject is irradiated withvisible light for at least about 40 seconds.
 44. The method of claim 37,wherein the macromer is polymerized by irradiating the subject withblue-green light.
 45. The method of claim 37, wherein the macromer ispolymerized by irradiating the subject with thermal energy.
 46. Themethod of claim 37, wherein the water soluble polymer is PEG.
 47. Themethod of claim 46, wherein the PEG has a molecular weight of from about10,000 to about 35,000 Daltons.
 48. The method of claim 37, wherein themacromer is biodegradable.
 49. The method of claim 37, wherein themacromer comprises a plurality of hydrolysable linkages.
 50. The methodof claim 49, wherein the hydrolyzable linkages are selected from thegroup consisting of esters or carbonates.
 51. The method of claim 37,wherein the water soluble polymer is modified with an poly (L-lactide)and poly (trimethylene carbonate) and an acrylate endcap.
 52. The methodof claim 51, wherein the water soluble polymer is PEG.
 53. The method ofclaim 37, wherein the composition further comprises a photo-initiator.54. The method of claim 53, wherein the photoinitiator is a dye.
 55. Themethod of claim 54, wherein the dye is eosin.
 56. The method of claim37, wherein the composition further comprises a rheology modifier. 57.The method of claim 56, wherein the rheology modifier is HA or CMC. 58.The method of claim 37, wherein the composition is substantially free oforganic solvent.
 59. The method of claim 37, wherein the hydrogel has astrain or elongation before fracture substantially similar to theexpected strain during normal use of the soft tissue to which itaugments or repairs.
 60. The method of claim 37, wherein the hydrogelhas a strain or elongation before fracture greater than the expectedstrain during normal use of the soft tissue to which it augments orrepairs.
 61. The method of claim 37, wherein the hydrogel has areversible elongation at least about 150% as great as an expected strainof the soft tissue which is augments or repairs.
 62. The method of claim37, wherein the hydrogel has an elastic modulus which is less than about150 kPa.
 63. The method of claim 37, wherein the hydrogen has anultimate yield stress of from about 500 to about 2,000 psi.
 64. Themethod of claim 37, wherein the macromer is injected subdermally. 65.The method of claim 64, wherein the macromer is polymerized byirradiating least a part of the skin of the subject.
 66. The method ofclaim 65, wherein the skin is irradiated for at least about 30 seconds.67. The method of claim 66, wherein the macromer is injectedintradermally.
 68. The method of claim 67, wherein the macromer ispolymerized by irradiating at least a part of the skin of the subject.69. The method of claim 68, wherein the skin is irradiated for at leastabout 30 seconds.
 70. The method of claim 37, further comprising shapingthe macromer.
 71. The method of claim 70, wherein the macromer is shapedduring polymerization of the macromer.
 72. The method of claim 71,wherein the macromer is polymerized by irradiating through the skin ofthe subject.
 73. The method of claim 37, comprising repeating steps a)and b) of claim 1 at least one time.
 74. The method of claim 37,comprising repeating steps a) and b) of claim 1 at least two times. 75.The method of claim 37, wherein the subject is a mammal.
 76. The methodof claim 75, wherein the subject is a human.
 77. The method of claim 37,the method comprising repairing facial tissue.
 78. The method of claim77, the method comprising decreasing the appearance of at least onefacial line, wrinkle, crease, or fold.
 79. The method of claim 37, themethod comprising augmenting breast, lip, cheek, chin, forehead,buttocks, hand, neck or earlobe tissue in a subject.
 80. The method ofclaim 37, the method comprising decreasing the appearance of a dermaldimple.
 81. The method of claim 80, wherein the dimple is a component ofa scar.
 82. The method of claim 37, wherein the composition isadministered with a red tinted syringe.
 83. The method of claim 37,wherein the soft tissue remains substantially augmented or repaired forat least about 1 month.
 84. The method of claim 83, wherein the softtissue remains substantially augmented or repaired for at least about 2months.
 85. The method of claim 84, wherein the soft tissue remainssubstantially augmented or repaired for at least about 6 months.
 86. Themethod of claim 37, wherein the hydrogel elicits a mild fibroticresponse in the subject.
 87. The method of claim 37, wherein thecomposition comprises a two part system, and wherein the polymerizationis initiated via a redox system.
 88. The method of claim 87, wherein thepolymerization occurs over a period of from about 30 seconds to about 2minutes.
 89. The method of claim 37, wherein the composition furthercomprises a drug such as an non-steroidal anti-inflammatory, ananalgesic, a vitamin such as E, C, A, D or K, an anti-oxidant, an alphahydroxyl acid such as lactic acid or a polymer capable of releasing suchdrug, vitamin, anti oxidant or alpha-hydroxyacid or any combinationthereof.
 90. A method of repairing or augmenting soft tissue in asubject, the method comprising a. injecting into a subject in needthereof a composition comprising a biodegradable, polymerizablemacromer, the macromer comprising a water soluble polymer modified withone or more biodegradable moieties; and b. polymerizing the macromer toprovide a hydrogel, thus repairing or augmenting the soft tissue.